1. Field of the Invention
The present invention relates generally to magnetic field sensors, and more specifically, to an integrated circuit including a semiconductor magnetic field sensor with a digital output.
2. Background of the Invention
Hall effect sensors and other semiconductor magnetic field sensors are widely used in applications in which it is desirable to provide a measurement of DC magnetic fields and relatively low frequency AC magnetic fields that are not otherwise easily sensed with coils or other antennas. Such applications include position and motion sensors for both linear and rotational motion, power supply and motor control applications in which the transformer or motor fields are detected, audio speaker applications in which the strength of the speaker's signal-induced field is detected, and lighting controllers for high-frequency energized lamps, such as sodium lamps.
Semiconductor magnetic field sensors are typically packaged as passive devices or with an integrated amplifier that amplifiers and/or buffers their output voltage. Since many of the applications for such sensors are in high noise and/or high intensity incident magnetic field environments which could otherwise affect operation of the sensor circuits, analog outputs are typically the only outputs provided on a die that includes the sensor, so that signal processing appropriate to the application can be applied by a circuit distant from the noise and/or high intensity incident magnetic fields. Also, for sensitive detection applications, the noise generated by the digital circuits included in an analog-to-digital converter (ADC) circuits can generate undesired magnetic field artifacts that are detected by the sensor. In particular, delta-sigma modulator-based ADC circuits typically generate currents at relatively high frequencies and over a wide bandwidth that make their incorporation on a die or in an integrated circuit package along with a semiconductor magnetic field sensor impractical. Delta-sigma modulator-based ADCs are very desirable for their relative simplicity and measurement linearity.
Therefore, it would be desirable to provide an integrated circuit including a semiconductor magnetic field sensor and having a digital output representative of the sensor output. It would further be desirable to provide such an integrated circuit that employs a delta-sigma modulator-based ADC for conversion of the sensor output.